Imaging devices, such as optical scanners, are well-known in the art and produce machine-readable image data signals that are representative of a scanned object, such as a photograph or a page of printed text. In a typical scanner application, the image data signals produced by an optical scanner may be used by a personal computer to reproduce an image of the scanned object on a suitable display device, such as a CRT or a printer.
A typical optical scanner includes illumination and optical systems to illuminate the object and to focus a small area of the illuminated object, usually referred to as a "scan line," onto the surface of a photosensitive detector positioned within the scanner. Image data representative of the entire object may then be obtained by sweeping the illuminated scan line across the entire object, either by moving the object with respect to the illumination and optical assemblies or by moving the illumination and optical assemblies relative to the object. In any event, the illumination system may include a suitable light source (e.g., a fluorescent or incandescent lamp or an array of light emitting diodes) to illuminate the object, whereas the optical system may include a lens and mirror assembly to direct and focus the image of the illuminated scan line onto the surface of the detector.
The photosensitive detector array used to detect the image light is typically a charge-coupled device (CCD), although other devices may also be used. A typical CCD may comprise a large number of individual cells or "pixels," each of which collects or builds-up an electrical charge in response to exposure to light. Since the size of the accumulated electrical charge in any given cell or pixel is related to the intensity and duration of the light exposure, a CCD may be used to detect light and dark spots on an image focused thereon. In a typical scanner application, the charge built up in each of the CCD cells or pixels is measured and then discharged at regular intervals, known as sampling intervals, which may be about 5 milliseconds or so for a typical scanner, although other sampling intervals may be used.
A hand-held or portable optical scanner is an optical scanner which is designed to be moved by hand across the object to be scanned, e.g., a page of text or a drawing or photograph. Such hand-held or portable optical scanners are well-known in the art and various components thereof are disclosed in U.S. Pat. No. 5,552,597 of McConica, and U.S. Pat. No. 5,586,212 of McConica, et al, which are hereby incorporated by reference for all that they disclose.
One problem associated with hand-held scanners is that they may be subjected to rough handling and occasionally may even be dropped onto the floor. Such rough handling and occasional dropping may place extreme shock loads on the various components of the hand-held scanner, and efforts are continually being made to ensure that the various components of the hand-held scanners can withstand such shock loads. One component of a typical hand-held scanner that is particularly sensitive to such shock loads is the optical assembly (i.e., the lens and mirror assemblies) that are used to direct and focus the image light onto the surface of the detector. If the optical assembly is not sufficiently immune to damage and/or misalignment from shock loads, the result can be an improperly focused image with a commensurate decrease in scanned image quality. In extreme cases, the resulting image data may be useless, requiring that the optical system be repaired and/or realigned before the scanner is again functional.